Australian application No. 46168/72 which corresponds to U.S. Pat. No. 4,189,378 describes a splitter having a blade extending vertically and mounted for rotation about an upright pivotal axis in relation to a conical or cylindrical take off in the floor of the sluice with the vertical blade diverting adjustable proportions of concentrate into the take off. Such devices have the disadvantage that the maximum adjustment range is limited by the necessarily planar face to the top of the take off at which the splitter rotates and the incorporation of such a planar surface into the floor of the helical sluice causes severe distortion to the normal shape of the latter with consequent flow distortion if the take off is of excessive diameter. In this case also, the protruding splitter blade causes severe flow disturbance when rotated to a position such that little or no concentrate is taken.
It is also known, to remove the amount of concentrate taken by providing a radial slot of adjustable length in the floor of sluice. Such a splitter is described in Australian Patent Specification No. 37175/78 which corresponds to U.S. Pat. No. 3,891,546. The disadvantages of such apparatus are that the adjustment mechanism is exposed to the solids in suspension which tend to jam the mechanism and, also, that the existence of the radial slot tends to weaken the structure of the sluice with increased probability of distortion and difficulty of manufacture.
The object of the present invention is an improved device for the splitting off and removal of a fraction of particles and which avoids or ameliorates the above mentioned disadvantages of previous splitters.